The invention relates to a control arrangement for an automobile occupant restraint system, comprising a microcomputer for processing acceleration signals provided by an acceleration pickup, and for supplying a trip signal to a trip device of the occupant restraint system, when the outcome the processed acceleration signals fulfill a criterion for activation of the occupant restrain system.
A similar control device is described in German patent 3,001,780, in which the microcomputer continuously monitors the acceleration signal supplied from the acceleration pickup and evaluates it in order, if appropriate, to send a trip signal to the trip device of the occupant restraint system. The occupant restraint system may be one of the airbag type or a safety belt type system with a belt pretensioning device.
Such control arrangements have to conform to extremely stringent requirements relating to functional security and reliability. It is just as necessary to ensure a proper activation as it is to preclude a spurious one. Since a microcomputer is required for the complex task of signal processing and determining the optimum points in time for tripping, the control arrangement contains a component essential for its operation which, owing to the operating conditions of an automobile, may be subject to a wide variety of interfering factors. There is thus a need for a monitoring arrangement which monitors the functioning of the microcomputer, and the operating factors necessary for its satisfactory operation, with the highest possible degree of reliability.